1. Field of the Invention
The present invention relates to an image recorder for directing an optical beam onto an image recording material such as a plate mounted on a drum to record an image on the image recording material.
2. Description of the Background Art
In such an image recorder, the formation of an accurately recorded image on a plate requires the reliable positioning of the plate (or image recording material) in a predetermined location on a drum. One of the known techniques for such positioning is as follows. At least two positioning pins are provided upright on the drum, and a hole is punched in the leading edge of a plate. The punched hole is brought into engagement with one of the two positioning pins, and a portion of the leading edge of the plate which has no punched hole is brought into contact with the other positioning pin, whereby the plate is positioned on the drum.
The above-mentioned technique improves the positioning accuracy of the plate on the drum. However, this technique becomes incapable of meeting the requirements if the range of usable plate sizes is expanded. The location of the punched hole must be changed depending on the expansion of the plate size range. The increase in the number of punchers is a solution to such a problem, but gives rise to the increase in costs.
In some cases, a hole (referred to as a printing hole) for use in a later step is punched at the same time that the above-mentioned hole for positioning is punched, in the image recorder. This provides a uniform positional relationship between the recorded image and the printing hole, thereby offering the advantage of improving an overprinting accuracy on a printing sheet.
There are a variety of standards for printing holes. For the adoption of one of the standards for printing holes, a puncher should be placed in a location compliant with the standard.
However, this location of the puncher sometimes competes with the location of a puncher being in actual use. In this case, it is impossible to use the printing hole based on the standard. Further, an attempt to punch printing holes based on a plurality of standards in the same image recorder increases the incidence of such competition.